Add compatibility with PostgreSQL 9.5 Fixes: #4

The incompatible changes have been introduced with commit
72d422a5227ef6f76f412486a395aba9f53bf3f0 during 9.5 development.

Ref: http://git.postgresql.org/gitweb/?p=postgresql.git;h=72d422a

Signed-off-by: Marco Nenciarini <marco.nenciarini@2ndquadrant.it>

pgespresso.c

@@ -77,11 +77,39 @@ pgespresso_start_backup(PG_FUNCTION_ARGS)
 		elog(DEBUG1, "updated ThisTimeLineID = %u", ThisTimeLineID);
 	}
 
+	/*
+	 * Starting from 9.5 the do_pg_start_backup caller needs to allocate the
+	 * 'pg_tblspc' directory and pass it as argument.
+	 *
+	 * Ref: http://git.postgresql.org/gitweb/?p=postgresql.git;h=72d422a
+	 */
+	#if PG_VERSION_NUM >= 90500
+	{
+		DIR	*dir;
+
+		/* Make sure we can open the directory with
+		   tablespaces in it */
+		dir = AllocateDir("pg_tblspc");
+
+		if (!dir)
+			ereport(ERROR,
+					(errmsg("could not open directory \"%s\": %m", "pg_tblspc")));
+
+		/*
+		 * We are not filling the tablespace map here.
+		 * This means that on 9.5 the 'tablespace_map' file has to be
+		 * generated by the invoker.
+		 */
+		do_pg_start_backup(backupidstr, fast, NULL, &labelfile,
+						   dir, NULL, NULL, false, false);
+
+		FreeDir(dir);
+	}
 	/*
 	 * Starting from 9.3 the do_pg_start_backup returns the timeline ID
 	 * in *starttli_p additional argument
 	 */
-	#if PG_VERSION_NUM >= 90300
+	#elif PG_VERSION_NUM >= 90300
 		do_pg_start_backup(backupidstr, fast, NULL, &labelfile);
 	#else
 		do_pg_start_backup(backupidstr, fast, &labelfile);